Due to the added deck height of the mighty RB30 block, the timing covers are left with a gap in the middle when a twin cam head is fitted (RB25, Neo or RB26). This extension plate fills that gap between the 2 covers. You will require the stock twin cam lower timing cover from an RB25/neo/26 and the extension can be spot welded or pop riveted onto the lower Nissan timing cover. 

Note: If using rivets, take notice of the depth of the rivet as long rivets may interfere with the timing belt causing belt failure. 

The extension made from stainless steel, and is supplied pre-folded as pictured.

*Some lower covers may require light manipulation of the joining lip to get a very snug fitment.